Carboxylic acid compounds including 4-(4-phenylbutoxy)benzoic acid of formula (3):
wherein n is an integer of 1 to 6, are useful as intermediates of medicines (see, for example, Patent Document 1). As a production method thereof, for example, a method in which an ester compound represented by the formula (4):
wherein R is a lower alkyl group, and a halogen compound represented by the formula (5):
wherein n is an integer of 1 to 6 and X is a halogen atom, are reacted in an organic solvent in the presence of a base, and then the reaction mixture is hydrolyzed is known (see, for example, Patent Document 1). According to this method, however, not only the reaction of the ester compound represented by the formula (4) and the halogen compound represented by the formula (5), but also a side reaction shown in the following scheme 1:
progresses, and thus, in addition to a desired ester compound represented by the formula (1)
wherein R and n are as defined above, a compound represented by the formula (2):
wherein R is as defined above, and a compound represented by the formula (6):
are also produced. Among these by-products, since the compound represented by the formula (2) has a similar chemical structure to that of the ester compound represented by the formula (1), it is difficult to separate the compound from the ester compound represented by the formula (1). In addition, when a mixture containing the ester compound represented by the formula (1) and the compound represented by the formula (2) is hydrolyzed, the compound represented by the formula (2), in addition to the ester compound represented by the formula (1), is hydrolyzed to a carboxylic acid represented by the formula (7):
wherein R is as defined above, which leads to a problem in that the carboxylic acid is contaminated in the objective carboxylic acid compound represented by the formula (3).Patent Document 1: Japanese Patent Application Laid-open Publication No. 3-95144